


actiones secundum fidei oneshots

by Minachi



Series: actiones secundum fidei [2]
Category: Undertale (Video Game)
Genre: Angst, DustHorror, F/M, M/M, Skeleton Sex (Undertale), Smut, There's A Tag For That, alternative endings
Language: English
Status: In-Progress
Published: 2020-12-23
Updated: 2021-01-11
Packaged: 2021-03-10 21:13:31
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings, Major Character Death, Rape/Non-Con
Chapters: 4
Words: 3,479
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28253712
Author URL: https://archiveofourown.org/users/Minachi/pseuds/Minachi
Summary: So I'm going to put oneshots from the actiones secundum fidei universe here.These will range from happening before the series started to off-screen events.Let me know if you have any requests, I can't promise I'll do them but I'll consider them at least.I might end up writing some onehots that don't contain smut so for now, titles that look like *this* contain smut and all others do not
Relationships: Sans (Undertale)/Reader, Sans/Sans (Undertale)
Series: actiones secundum fidei [2]
Series URL: https://archiveofourown.org/series/2069691
Comments: 29
Kudos: 54





	1. *DustHorror*

**Notes for the Chapter:**

> So I tried to write a smutty oneshot about DustHorror in the **actiones secundum fidei** universe...  
> I ended up writing more plot and back story than porn, I think.  
> ...  
> Consider this cannon to the **actiones secundum fidei** and let me know what you think.  
> Please tell me if you think its good or not and if you want me to write more smut for **actiones secundum fidei**  
>  This is the first smut I've ever written  
> 😳  
> 👉👈
> 
> No warnings for now but that'll definitely change if I write smut of reader in **actiones secundum fidei**

Some time ago, before Cross joined, there was an unexpected shift in the dynamics of Nightmare’s gang.

Nightmare is, obviously, the leader. He always had been and would be eternally.

Killer is Nightmare’s unofficial right hand. Despite his insanity, he's a skilled manipulator, very adept at persuading others. Killer is  perpetually cheerful and playful, he loves to tease others. This demeanor becomes unsettling when it doesn’t waver even as he slices his way through monsters and humans alike. 

Dust is the magical powerhouse of the gang. All the LV he gained gives him a great advantage in magic and strength. However, all the LV affects his soul, leaving it constantly craving for more. More violence, more death, and invariably more LV. Dust never stops muttering to his Papyrus, occasionally bringing up the long-dead human from his timeline. 

Horror, after his head injury and years of starvation, has low magic reserves compared to the others. Horror, does, however, possess a physical ability that far surpasses the others. While mainly relying on his trusty ax, Horror occasionally can use bone attacks. Unfortunately, Horror’s amnesia and occasional bouts of psychosis sometimes make him a threat to his fellow gang members.

It was during one such bout of psychosis that the dynamic changed. Not from Horror, but from Dust. The castle had been quiet for a while, no raids or battles with the Star  Sanses .

Dust and Killer would frequently ‘spar’. Their spars mainly consist of Killer easily dodging Dust’s attacks while taunting him playfully. As pissed as it got Dust, it let him manage the urge for fighting all his LV gave him.

Killer was nowhere to be found for some reason, unimportant to Dust. All his urges, his compulsions for destruction, for power drive him insane. Well, more insane than he already is.

He passed Horror at a few points as he wandered the halls, occasionally blasting walls for no reason. Horror was a monster of few words, having been recruited from a world where  Aliza completed a genocide of the underground. He didn't acknowledge it, either forgetting or repressing the memory of what happened to his home.

Dust and Horror got along quite well, despite not having many conversations. They were similar in a way, both twisted into an unrecognizable existence after a significant  shift in their magic. As Horror’s memory and mental stability faded, he grew sadistic and callous. As Dust gained LV, his guilty conscience fell away and  ultimately twisted into a perverted joy.

Unfortunately, Dust was so driven by the need for LV that he didn’t recognize Horror as he pounced on him. Luckily for Horror, he was in a moment of relative clarity, allowing him to react quickly.

Horror was able to throw Dust off and  dodge the  Gaster Blaster that shot at him immediately after. Not wanting to  hurt Dust, Horror threw up a wall of bones to separate them.

The familiar magic snapped Dust out of his haze. The desire for 'bloodshed' was still surging in him, but he recognized Horror.

“ Hehe ,” Dust’s cackle echoed through the hallway. “Sorry bout that. I’m just looking for some LV.”

Horror drops the bone wall  slowly , his left eye socket glowing red. He's cautiously wary of Dust but confident he could get away safely if need be.

“Ehhh, that’s so crass Paps,” Dust said to himself. “I’ve never even considered it.”

Horror was perplexed by the half conversion, but not particularly worried as that was the norm with Dust.

Dust suddenly grinned, giving Horror a look he didn’t recognize. Unsure now, Horror prepared to shortcut away, but Dust beat him to it.

One second Dust was in front of him, the next bony arms behind him wrapped around him, and he was dragged through the void.

Horror let out a yelp as he  abruptly fell on a bed, the loudest noise he’d  formed so far. He immediately tried to lash out at Dust, knowing he could knock him back a fair bit.

Horror was too slow and Dust slammed him down with blue magic. Horror found himself on his back in a bed, Dust grinning eerily above him. Dust was muttering softly to Papyrus, Horror couldn't make out what he was saying.

“So...” Dust started a deep purr in his voice that had Horror shuddering. “ I gotta _proposition_ for ya.”

An audible silence dragged out before Horror  grasped Dust was waiting for a response. 

“What...do you...mean?” Horror managed to get out, slowly. He had trouble speaking  at times due to the huge crater in his skull.

“My LV gimmes violence cravings,” Dust said gleefully. “The urge to dominate, in some way, _any_ way.”

Horror wasn’t sure what Dust meant by that or how he was supposed to help.

“If I could dominate in let’s say,” Dust chuckled. “A _different_ way, if ya catch my drift.”

Dust punctuated his  remark with the winking of an eyelight , baffling Horror further.

“Maybe then,” Dust continued. “I could calm down a bit, ya know?

Dust smiled, taking on that look that confused Horror. His lucidity was  fleeing and he began to dissociate as he was pinned to the bed.

Dust seemed to notice this, letting his magic go, which brought Horror back to the present as the hold on his soul was released.

“I really like ya, so I’m trying to be nice here.”  Dust growled unexpectedly, giving Horror whiplash at the abrupt  switch in the mood. “I’m asking if I can fuck ya, although I’m not sure I’d be able to stop myself if ya refuse.”

It takes Horror a moment to comprehend what he just heard. He can scarcely wrap his head around it. Dust was propositioning him for sex?

He hasn't ever noticed Dust having any partners, and he literally couldn't remember the last  occasion he had one. As Dust growled  once again , Horror's mind spun and came to a snap-second decision.

“It's ok,” Horror mutters quietly, red magic flushing slightly on his face.

Horror thought Dust’s grin couldn't get any wider, but he was oh so wrong. At the verbal confirmation, Dust didn't waste his chance to get busy.

Dust tore through their clothes  and roughly smashed his teeth against Horror. Caught off guard, Horror struggled to remember how to summon that magic.

Summoning a tongue was simplest, and Horror let Dust hungrily invade his mouth. Dust moaned in the sloppy kiss, creating a sensation that was foreign to Horror, but not unpleasant. 

Dust actually, physically grabbed Horror’s soul, which dragged a strangled moan out of him. No one had touched Horror’s soul as far as he could remember. 

Somehow, using intention-imbued magic, Dust triggered Horror into summoning an entrance for him.

Horror dimly realized that Dust intended to top, and his apprehension shot up as he’s never bottomed  previously .

Dust, uncharacteristically silent, seemed to understand this. Another gaze, a lustful one Horror now  understood , was shot at him as Dust stuck a  phalange in him.

A gasp left Horror at the strange sensation, he couldn't decide if it was painful or pleasant.

Then Dust’s  phalange curled and hit something that  caused Horror to keen, which Dust laughed in satisfaction at.

Dust continued to simulate Horror, adding additional phalanges and curling them in ways that made him see stars. 

Horror whimpered as it became too much, a sudden curl of fingers sending him over the edge.

Dust pulled out his fingers and licked the red magic off them, to Horror’s embarrassment. Horror hid his face in his hands as if that would protect him from that hungry gaze.

Horror heard laughter and  sensed Dust  grasp his legs, straddling him. This, he  knew , was it. He unconsciously tensed, trepidation rising as he thought about the next part.

Dust didn’t do as he expected though, merely trailing his fingers over Horror’s bones. He sounded like he was humming, or maybe purring? It lulled Horror back into a sense of security.

Dust adjusted their positions and Horror definitely noticed Dust’s magic bumping against his. Surprisingly, it set off an eagerness that overcame his anxiety. Suddenly all he wanted was for the two of them to be connected, and he unintentionally thrust his hips up at the thought.

A phalanx was rubbing circles on his ilium, making Horror wonder what Dust was waiting for. Permission he  comprehended as the rubbing became frenzied and insistent. Horror squeezed his femurs around Dust, hoping that would get his answer across.

It did and flipped some kind of switch in Dust. He was  swiftly deep in Horror’s magic, fingers grabbing and groping at Horror’s body. 

Horror’s own hands fell to his sides, barely able to catch his breath at the sudden  shift in pace. Dust pounded him unrelentingly. Sparks of pleasure broke through Horror’s barely cognizant state. He let out embarrassingly vocal moans and whimpers unconsciously.

Dust seemed similarly distant, eyelights fixed on Horror without a sense of recognition. His phalanges had found tight grips on Horror’s ilium and ribcage .

The only  noises Dust let out were deep growls and panting breaths. His movements frenzied and desperate, but catching on the spots that  produce pleasure that rattles up Horror’s bones. 

“Horror”, Dust grinds out, not slowing his pace. 

“Say my name,” Dust demanded. His eye lights focus on Horror’s. His ever-present grin was gone , he almost looked possessive.

“Du--,” Horror tried to comply but a new angle cut off his words into a moan.

Dust chuckled at this and slowed to let Horror get his voice out.

Given a chance to take a breath, Horror managed to say it. “Dust, _ahhh~_ ”

At his name, Dust put a lot more force into his next thrust.

“Again,” He commanded, a growl deepening his voice

Horror did and Dust kept demanding him to call his name until Horror could barely moan, let alone speak.

“Fuck,” Dust vocally groaned, a husky edge to his voice. “Ya so perfect, haaaahh~”

That sparked something intangible in Horror, and he ended up clenching hard, finally pushing Dust over the edge.

Dust  sighed loudly, pushing himself further in as he spilled his magic. Horror could not have ever imagined it was possible to be this close to another monster. The feeling of magic coating his insides was surprisingly quite pleasant. The magic ended up being absorbed, giving Horror a sensation of completeness he couldn’t describe.

Despite finishing, Dust didn't pull out or dismiss his magic. He waited for their magic to dissolve naturally and kept holding Horror close. The room was filled with the sound of breathing, Dust’s low and panting while Horror’s quiet and shallow. 

For the first time in recent memory, Horror didn’t feel hungry or threatened. He  enjoyed an emotion close to contentment. He’d wasn’t able to articulate it himself, but he actually  considered his surroundings safe and acknowledged a feeling akin to happiness with Dust.

Dust was in the same boat, the murderous urges of his LV having been soothed almost completely for the first time. He didn’t notice anything from his Papyrus, all his attention being focused on Horror, that night.

The two of them never talked about what happened that night, or the many repeats after that. It quickly became uncommon to see one without the other.

Nightmare noticed the increase in positive feelings, but the improvement in their teamwork balanced it out for him.  Killer shipped it and teased them but they were unbothered. However, Horror landed a harsh blow on Killer after discovering that Killer had recorded them one night. The footage was deleted and Killer never attempted that again.

To outsiders, Horror and Dust have a  dangerous codependency, worsened by their own unstable minds. But for them, they managed to soothe each other’s urges, smoothing out alittle of the frayed part of themselves.

Is it love? Who can say? Words of affection are tossed around, but Dust and Horror are a bit too broken to consider love. They simply cling to each other and find comfort in the kindred damage  of their souls.

**Notes for the Chapter:**

> So... that was a thing
> 
> Please let me know what you think.  
> I appreciate all feedback, critical or positive, constructive, or not.
> 
> And does anybody want smut for **actiones secundum fidei**?


	2. Alternate Chapter 10 Endings

**Notes for the Chapter:**

> I put my rough outline into this, it was more difficult than I thought 😅
> 
> If you guys like it though, I'll just start using the mind maps for my outlines so I can post them later


	3. Alternative Kindness Soul Endings

**Feel?**

Angry/Sad/Afraid -> next choice

Numb -> Narrator offers reset

**Should you try to call for help?**

No

But nobody came

Narrator mercy resets

Very angsty goodbye from the narrator

Yes, try to reach anyone other than Nightmare

Error will show up

Yes, try to summon Dream or Ink

_If sad/angry_

Summon Dream

_if afraid/numb_

Summon Ink with ink found on Nightmare’s desk

Yes, try to reach Night underneath the corruption

Wait for Nightmare to show up

_All Possible Endings_

**Dream Endings**

If you beg for help, Dream will take you away.

You’ll be affected by Dream’s positive aura and become somewhat dependent on him.

Dream will be able to feed on the positivity of your kindness soul.

Open-ended ending, friends or something more?

NEUTRAL END

If you ask Dream to kill you, he’ll refuse and take you away.

Chains you up for ‘your own safety’ 

Ends up keeping you like a doll. 

Dream’s positive aura makes you happy even as he uses your body. 

Always claims he’s only protecting you

Nsfw noncon 

BAD END

If you do nothing when Dream appears, he’ll try to get a response and eventually just take you.

Dream is secretly happy that you don’t end up being affected by his aura.

You dissociate and Dream ends taking care of you. 

Dream uses your body and creepily talks about love, implied yandere

Nsfw noncon

BAD END

If you cling to Dream and seek comfort, he’ll console you and take you away.

You recover (mentally and physically) and end up staying with him. 

Implied happy ending with yandere dream vibes

Sweet nsfw excerpt from your relationship with Dream after recovering.

GOOD END? (You left Night behind and never tell Dream about him)

* * *

**Error Endings**

If you beg Error for help, you'll shock him.

When he recovers, Error will open a portal to the anti void

He’ll pull you in with his strings, but keep his distance from you.

Error will be obviously uncomfortable when you cry

When you calm down, Error will ask what you want to do next

You ask if he can stay with you

Error pretends that he doesn’t want that/ it’ll be temporary (tsundere vibes)

Error and you eventually grow close.

The tough-love narrator ends up being a good match for Error and isn’t affected by the voices in the anti-void

Fluffy nsfw

GOOD END

If you ask Error to kill you, he’s astonished and asks why.

You don’t answer and Error looks around and realizes the situation

Error will take you to anti void and asks if you’re sure you want to die.

When you confirm, Error will break your neck with his strings. The death will be instantaneous and painless.

A short excerpt of Error making a doll of you in his anti-void and saying that he wishes he got to you before Nightmare

DEAD END

If you do nothing when Error appears, he’ll pity you.

Error will comment that you look like a puppet with its strings cut

Error will then take you to anti-void, what happens next depends on how your first answer.

_If angry/sad/afraid:_

You’ll recover and eventually grow close to Error. 

Fluffy nsfw

GOOD END

_If numb_

You remain dissociated and Error wraps your soul in strings, getting rid of your body

BAD END

If you try to cling to Error and seek comfort, he’ll glitch a lot.

Error almost reboots when you approach him, and strings you up

After realizing the situation he takes you to Outertale

He keeps you at a distance but starts talking about stars

You eventually calm down

You ask if he can stay with you

He says you can, gives you a chocolate bar, and takes you to antivoid

Error and you eventually grow close.

The tough love narrator ends up being a good match for Error and isn’t affected by the voices in the anti-void

Fluffy nsfw

GOOD END

* * *

**Ink Endings**

If you beg Ink for help, he’ll laugh at you

Ink will remind you that you chose this, and leave

Enter nightmare route

If you ask Ink to kill you, he’ll do it immediately without any hesitation.

DEAD END

If you do nothing when Ink arrives, there are 2 possible paths.

_If numb_

Ink looks at you with curiosity, says you remind him of himself after his eraser, takes you

Keeps you, uses you for body and something he can say he has more emotions than

Nsfw noncon

BAD END

_If angry/sad/afraid_

Ink will ask why you bothered calling and if you gave Error his message

Ink laughs when you don’t respond, and leaves

Enter Nightmare route

If you cling to and seek comfort from Ink, he’ll be confused.

Ink decides to take you, saying that your confusing actions are interesting

You eventually fall in love with the soulless being, and it’s implied he feels the same way on his vials.

However, Ink accidentally forgets you, leaving you somewhere you end up dying.

Ink is so devastated that he gets rid of all traces of you. Ink purposely doesn’t want to remember you.

It’s like you never existed at all

DEAD END/BAD END

* * *

**Nightmare and Night Endings**

If you beg for help, the path depends on your answer to the first question.

_If numb_

Nightmare will laugh, and Night will fail to regain control.

Nightmare kills you

DEAD END

_If angry/sad_

Enter seek comfort route

_If afraid_

Night fails to keep control after regaining it for a few moments

Enters the do-nothing route

If you ask Nightmare to kill you, Night will gain control

Night begs you to not give up, the next part depends on your first answer.

_If numb_

Nightmare will take back control and kill you

DEAD END

_If angry/sad/afraid_

Night will keep control and run away with you.

Night ends up reuniting with Dream who is overjoyed to see his true brother again.

Dream completely seals the corruption away.

You eventually recover and end up with both Night and Dream

Night feels guilty about abandoning the corruption

Dream gives off yandere vibes for both you and Night

GOOD END?

If you do nothing when Nightmare appears, the path depends on your first answer

_If numb_

Nightmare kills you, claiming its a mercy to get rid of a broken doll

DEAD END

_If angry/sad/afraid_

Nightmare will end up keeping you alive.

Nightmare will use you for your negative emotions and body

Occasionally lets Killer ‘play’ with you

There’s no sign of Night ever again 

BAD END

If you cling to Nightmare and try to seek comfort, Night gains control

Night breaks down, apologizing, seeking comfort from you.

You end up consoling him and ask him to explain the corruption in detail

You have a meaningful heart to heart with Night

You help Night be more confident and reveal himself to others

You grow close to Night and become acquainted with everyone in the castle.

Nightmare resurfaces and threatens you, saying he’ll kill you if you hurt Night

To his surprise, you tell him you forgive him.

You tell him that you understand that he was lashing out, afraid that he might lose Night

You also deny the possibility of ever hurting Night, you love him.

A begrudging truce with Nightmare eventually leads him to make amends.

You end up living happily with both Night and Nightmare in their castle

Implied help with Night and Dream relationship

Fluffy nsfw w/ both Night and Nightmare

GOOD END


	4. Ink's To Do List

**Notes for the Chapter:**

> This is just for fun, but it does have some tidbits about the relationships in my multiverse.

**Ink’s To-Do List**

  * Dream

    * Best friend

    * I’m immune to his aura

    * A friend with ‘benefits’ occasionally, a switch

  * Geno

    * Tsundere

    * ~~Have a real connection?~~

    * ~~Still missing from save screen~~

    * Different Geno appeared after reset

  * Reaper

    * You’re immune to his death touch

    * TOO CLINGY

    * Never again! He’ll try to trap you

    * ~~He’s been bugging Geno, stop him~~

    * Got together with the new Geno

  * Fresh

    * No

    * Do not let him spread his ‘fresh vibes’

    * Introduce to Error

  * Nightmare

    * Good after using negative vials

    * Get photo evidence for Dream/ blackmail Nightmare

    * Goop doesn’t wash out

  * Killer

    * Never happened, never will

    * ~~We both swore never to speak of it~~

  * X!Gaster

    * A new creator!

    * He’s so shy, its cute

    * He seems different

    * I’m glad he keeps trying, but

    * ~~I had a bad time~~

    * I’m out

  * Cross

    * New friend! ~~Out of guilt~~

    * Cross is pretty different from other Sanses

    * ~~I have to tell him I can’t fix his universe~~

    * I’m not sure I did the right thing, maybe I should ask Dream?

    * Everyone seems to enjoy my ‘comfort’ though

    * Cross ~~is missing~~ joined Nightmare

  * Error

    * ~~Stop from destroying AUs~~

    * Don’t create anything

      * Truce with Error

    * Watch Undernovela with Error

    * Error’s afraid of Fresh

      * XD he rebooted after less than a minute when meeting him

    * Invite Error to date in Outertale

    * Bug Nightmare for advice

    * Give Error chocolate

    * Ask Lust!Sans for advice




**Notes for the Chapter:**

> I headcanon Ink as a hoe. (at first glance)  
> Ink's willing to jump into bed with almost anyone, it's an easy way to experience intimacy.  
> The creator said she's fine with people writing ink with a different sexuality/gender. She wanted him to be a character fans can use in their own unique ways.


End file.
